/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.confignode.manager.load.balancer.router;

import org.apache.iotdb.common.rpc.thrift.TConsensusGroupId;
import org.apache.iotdb.common.rpc.thrift.TRegionReplicaSet;
import org.apache.iotdb.commons.utils.ThriftCommonsSerDeUtils;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;
import org.apache.thrift.TException;
import org.apache.thrift.protocol.TProtocol;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;

public class RegionRouteMap {

    // Map<RegionGroupId, LeaderDataNodeId>
    private Map<TConsensusGroupId, Integer> regionLeaderMap;

    // Map<RegionGroupId, TRegionReplicaSet>
    // Indicate the routing priority of read/write requests for each RegionGroup.
    // The replica with higher sorting result have higher priority.
    // TODO: Might be split into readRouteMap and writeRouteMap in the future
    private Map<TConsensusGroupId, TRegionReplicaSet> regionPriorityMap;

    public RegionRouteMap() {
        this.regionLeaderMap = new ConcurrentHashMap<>();
        this.regionPriorityMap = new ConcurrentHashMap<>();
    }

    /**
     * @return DataNodeId where the specified RegionGroup's leader resides. And return -1 if the
     * leader is not recorded yet
     */
    public int getLeader(TConsensusGroupId regionGroupId) {
        return regionLeaderMap.getOrDefault(regionGroupId, -1);
    }

    public void setLeader(TConsensusGroupId regionGroupId, int leaderId) {
        regionLeaderMap.put(regionGroupId, leaderId);
    }

    public Map<TConsensusGroupId, Integer> getRegionLeaderMap() {
        return regionLeaderMap;
    }

    public void setRegionLeaderMap(Map<TConsensusGroupId, Integer> regionLeaderMap) {
        this.regionLeaderMap = regionLeaderMap;
    }

    public Map<TConsensusGroupId, TRegionReplicaSet> getRegionPriorityMap() {
        return regionPriorityMap;
    }

    public boolean isEmpty() {
        return regionLeaderMap.isEmpty() && regionPriorityMap.isEmpty();
    }

    public void setRegionPriorityMap(Map<TConsensusGroupId, TRegionReplicaSet> regionPriorityMap) {
        this.regionPriorityMap = regionPriorityMap;
    }

    public void removeRegionRouteCache(TConsensusGroupId regionGroupId) {
        this.regionLeaderMap.remove(regionGroupId);
        this.regionPriorityMap.remove(regionGroupId);
    }

    public void serialize(OutputStream stream, TProtocol protocol) throws IOException {
        try {
            ReadWriteIOUtils.write(regionLeaderMap.size(), stream);
            for (Map.Entry<TConsensusGroupId, Integer> leaderEntry : regionLeaderMap.entrySet()) {
                leaderEntry.getKey().write(protocol);
                ReadWriteIOUtils.write(leaderEntry.getValue(), stream);
            }

            ReadWriteIOUtils.write(regionPriorityMap.size(), stream);
            for (Map.Entry<TConsensusGroupId, TRegionReplicaSet> priorityEntry :
                    regionPriorityMap.entrySet()) {
                priorityEntry.getKey().write(protocol);
                priorityEntry.getValue().write(protocol);
            }
        } catch (TException e) {
            throw new IOException(e);
        }
    }

    // Deserializer for consensus-write
    public void deserialize(ByteBuffer buffer) {
        this.regionLeaderMap = new ConcurrentHashMap<>();
        int leaderEntryNum = buffer.getInt();
        for (int i = 0; i < leaderEntryNum; i++) {
            TConsensusGroupId regionGroupId =
                    ThriftCommonsSerDeUtils.deserializeTConsensusGroupId(buffer);
            int leaderId = buffer.getInt();
            regionLeaderMap.put(regionGroupId, leaderId);
        }

        this.regionPriorityMap = new ConcurrentHashMap<>();
        int priorityEntryNum = buffer.getInt();
        for (int i = 0; i < priorityEntryNum; i++) {
            TConsensusGroupId regionGroupId =
                    ThriftCommonsSerDeUtils.deserializeTConsensusGroupId(buffer);
            TRegionReplicaSet regionReplicaSet =
                    ThriftCommonsSerDeUtils.deserializeTRegionReplicaSet(buffer);
            regionPriorityMap.put(regionGroupId, regionReplicaSet);
        }
    }

    // Deserializer for snapshot
    public void deserialize(InputStream stream, TProtocol protocol) throws IOException, TException {
        this.regionLeaderMap = new ConcurrentHashMap<>();
        int leaderEntryNum = ReadWriteIOUtils.readInt(stream);
        for (int i = 0; i < leaderEntryNum; i++) {
            TConsensusGroupId regionGroupId = new TConsensusGroupId();
            regionGroupId.read(protocol);
            int leaderId = ReadWriteIOUtils.readInt(stream);
            regionLeaderMap.put(regionGroupId, leaderId);
        }

        this.regionPriorityMap = new ConcurrentHashMap<>();
        int priorityEntryNum = ReadWriteIOUtils.readInt(stream);
        for (int i = 0; i < priorityEntryNum; i++) {
            TConsensusGroupId regionGroupId = new TConsensusGroupId();
            regionGroupId.read(protocol);
            TRegionReplicaSet regionReplicaSet = new TRegionReplicaSet();
            regionReplicaSet.read(protocol);
            regionPriorityMap.put(regionGroupId, regionReplicaSet);
        }
    }

    public void clear() {
        regionLeaderMap.clear();
        regionPriorityMap.clear();
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        RegionRouteMap that = (RegionRouteMap) o;
        return regionLeaderMap.equals(that.regionLeaderMap)
                && regionPriorityMap.equals(that.regionPriorityMap);
    }

    @Override
    public int hashCode() {
        return Objects.hash(regionLeaderMap, regionPriorityMap);
    }
}
